A first-principles study of MgSnN2 films using a DFT-1/2 approach

Abstract

The thin films of a newly discovered MgSnN2 Pnma phase were computationally investigated using a recently developed DFT-1/2 functional. It was showing that the properties of the investigated films closely relate to the thickness. For those films with odd number of layers, the band gaps are accordingly 2.040 eV, 2.102 eV and 2.107 eV for three, five and seven layers, showing an increasing order along with depth. As for those with even number of layers, the band gaps show a reduction from 2.488 eV for double layer to 2.210 eV for four-layer and then to 2.136 eV for six-layer. The change of the band gap mainly comes from the intralayer and interlayer bonding relation. The valence and conduction band edges increase monotonically along with the number of layers of thin films, except for the conduction band edge of double layer. Moreover, the absorption spectra shows promising absorption peaks within visible range. Therefore, fabrication of films with thickness control can potentially be used to expand the applications of MgSnN2 for energy harvest, photocatalysis, electronic and optoelectronic devices.